In this connection, in recent years there has been increased use of mobile devices, such as smart phones, tablets and portable media players. One popular use of such devices is to provide location relevant information, such as maps. For example, many mobile devices now have GPS functionality incorporated, which allows their current location to be displayed on a map and, for example, allows the user to obtain directions or information about nearby attractions.
A problem with GPS is that it is not always very accurate and is often slow. For example, GPS works well for in-car navigation because multiple measurements can be taken as the vehicle moves along a number of fixed paths (i.e. roads). This allows the system to generate an apparently accurate location result, even though the raw data itself may contain timing and positional errors. However, for slow moving bodies which have more freedom of movement (e.g. such as a user on foot), GPS often does not provide sufficiently accurate results. Furthermore, GPS often cannot operate in interior locations since a GPS receiver requires unobstructed line of sight with four GPS satellites. The GPS signals are therefore not able to penetrate a building's walls or underground locations. Moreover, GPS also cannot distinguish between different elevations and therefore it cannot be used to provide information as to which floor of a building a user is on. This limits the applications of GPS location systems. As such, a navigation system relying on GPS is wholly unsuitable for use by a user inside a multi-storey building, such as a multi-storey shopping mall, museum or car park.
Accordingly, the present invention seeks to address some of the problems associated with GPS location systems.